Patent Literature 1 discloses an exemplary package that represents a system of hermetically sealing a lead terminal in a lead terminal sealing hole using a glass material. The exemplary package disclosed in Patent Literature 1 includes a metal container. A bottom portion or a side wall portion of the metal container has a plurality of lead terminal sealing holes (hereinafter referred to simply as terminal sealing holes). A glass material is applied to the terminal sealing holes to thereby hermetically seal the lead terminals.
The system disclosed in Patent Literature 1 provides one terminal sealing hole for each lead terminal. This system has a limit to the number of lead terminals to be housed at one time, as encountered when an integrated circuit (IC) or other metal package is to be designed. Take, for example, a square Kovar metal package having one side measuring 50 mm in length. To drill terminal sealing holes in a wall surface of the package in order to house the corresponding number of lead terminals, the number of lead terminals per side is limited to 38. The package has a configuration in which lead terminals are extended from all four sides. When the total number of pins is 352, for example, it becomes necessary to house 88 (=352/4) lead terminals in one hole. To increase the number of external terminals in metal packages, a plurality of lead terminals needs to be housed in one terminal sealing hole.
Patent Literature 2 discloses a metal package structure that allows a plurality of conductors to be sealed in one terminal sealing hole. The metal package disclosed in Patent Literature 2, however, includes conductors metalized on a ceramic segment instead of having a lead shape. Thus, when a ceramic substrate having a metalized conductor is passed through a glass sealing frame formed on a wall surface of an IC or other metal package, no device is available to connect to a motherboard on which the metal package is mounted, or it is extremely inconvenient to connect to the motherboard. This is because of the following reasons. Specifically, wiring of the ceramic substrate defies soldering for mounting the ceramic substrate on the motherboard. Moreover, performing wire bonding requires that surface treatment be changed. Performing wire bonding for wiring connections on the inside of the package involves bonding of the ceramic substrate that protrudes horizontally like eaves on the inside of the package. In this case, however, a plurality of wires is connected to one ceramic substrate. This connection step can damage the ceramic substrate due to, for example, bonding load and ultrasonic waves.